The successful absorption of bacteriophage to these transformed strains does not necessarily result in a successful infection. These results indicate the complex nature of bacteriophage resistance in B. subtilis. Additionally, utilizing the processes of transformation and transfection, it appears that bacteriophage DNA is discriminated against in these four strains. These results suggest the acquisition and/or activation of nucleases in the transformed strains which were not present in the parent 168 strain. The action of these nucleases is presently under investigation. This research is designed to elucidate the types of molecules used as viral receptors on cell surfaces.